:root {
  --color-page: #EEF1FB;
  --color-panel: #F8F9FE;
  --color-panel-deep: #E3E7F7;
  --color-border: #CCD3EC;
  --color-accent: #4756C4;
  --color-accent-deep: #35419B;
  --color-text: #23283F;
  --color-text-soft: #5B6180;
  --color-success: #2F9E6E;
  --color-warning: #C9862B;
  --color-error: #C4485B;
  --color-flag-red: #CE3D48;
  --color-flag-blue: #31459B;
  --color-flag-white: #FDFDFE;
  --color-focus-shadow: rgba(71, 86, 196, 0.2);
  --color-card-shadow: rgba(71, 86, 196, 0.22);
  --color-card-shadow-soft: rgba(71, 86, 196, 0.1);
  --color-button-shadow: rgba(71, 86, 196, 0.45);
  --color-overlay: rgba(35, 40, 63, 0.46);
  --font-display: "Inter", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Inter", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Consolas, "Courier New", monospace;
  --radius-small: 10px;
  --radius-medium: 16px;
  --radius-large: 28px;
  --radius-pill: 999px;
  --shadow-card: 0 30px 70px -34px var(--color-card-shadow), 0 6px 18px -8px var(--color-card-shadow-soft);
  --shadow-button: 0 10px 24px -10px var(--color-button-shadow);
  --content-width: 1240px;
  --reading-width: 820px;
  --header-height: 72px;
  --gutter: clamp(16px, 4vw, 40px);
  --section-space: clamp(64px, 9vw, 112px);
  --focus-ring: 2px solid var(--color-accent);
  --toc-offset: 92px;
  --transition-fast: 160ms ease;
  --transition-slow: 600ms cubic-bezier(0.22, 1, 0.36, 1);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  min-width: 320px;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 16px);
}

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 320px;
  margin: 0;
  overflow-x: clip;
  background: var(--color-page);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

img,
svg,
video,
canvas {
  display: block;
  max-width: 100%;
}

img {
  height: auto;
}

button,
input,
select,
textarea {
  color: inherit;
  font: inherit;
}

button {
  cursor: pointer;
}

a {
  color: inherit;
  text-decoration: none;
}

p,
ul,
ol,
blockquote,
pre,
table {
  margin-top: 0;
}

p:last-child,
ul:last-child,
ol:last-child,
blockquote:last-child {
  margin-bottom: 0;
}

h1,
h2,
h3,
h4 {
  margin-top: 0;
  color: var(--color-text);
  font-family: var(--font-display);
  text-wrap: balance;
}

h1 {
  margin-bottom: 24px;
  font-size: clamp(52px, 6vw, 72px);
  font-weight: 800;
  letter-spacing: -0.015em;
  line-height: 1.12;
}

h2 {
  margin-bottom: 18px;
  font-size: clamp(34px, 4vw, 52px);
  font-weight: 800;
  letter-spacing: -0.012em;
  line-height: 1.18;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(22px, 2.4vw, 30px);
  font-weight: 750;
  line-height: 1.28;
}

h4 {
  margin-bottom: 8px;
  font-size: 18px;
  font-weight: 700;
}

strong {
  font-weight: 750;
}

code,
kbd,
samp {
  font-family: var(--font-mono);
  overflow-wrap: anywhere;
}

code {
  padding: 0.12em 0.38em;
  border-radius: var(--radius-small);
  background: var(--color-panel-deep);
}

pre {
  max-width: 100%;
  padding: 20px;
  overflow-x: auto;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-medium);
  background: var(--color-panel);
  -webkit-overflow-scrolling: touch;
}

pre code {
  padding: 0;
  background: transparent;
  overflow-wrap: normal;
}

:where(a, button, input, select, textarea, summary, [role="tab"]):focus-visible {
  outline: var(--focus-ring);
  outline-offset: 3px;
}

::selection {
  background: var(--color-panel-deep);
  color: var(--color-accent-deep);
}

.wrap {
  width: 100%;
  max-width: var(--content-width);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.reading-wrap {
  width: 100%;
  max-width: calc(var(--reading-width) + var(--gutter) + var(--gutter));
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section {
  padding-top: var(--section-space);
  padding-bottom: var(--section-space);
}

.section-compact {
  padding-top: calc(var(--section-space) * 0.62);
  padding-bottom: calc(var(--section-space) * 0.62);
}

.section-head {
  max-width: 760px;
  margin-bottom: 38px;
}

.section-head-center {
  margin-inline: auto;
  text-align: center;
}

.eyebrow {
  margin-bottom: 12px;
  color: var(--color-accent-deep);
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.lead {
  max-width: 760px;
  color: var(--color-text-soft);
  font-size: clamp(18px, 2vw, 22px);
  line-height: 1.65;
}

.muted {
  color: var(--color-text-soft);
}

.accent-text,
.kw {
  color: var(--color-accent);
}

.no-break {
  white-space: nowrap;
}

.panel,
.card {
  min-width: 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-large);
  background: var(--color-panel);
}

.card {
  padding: clamp(22px, 3vw, 32px);
  box-shadow: var(--shadow-card);
}

.panel-deep {
  background: var(--color-panel-deep);
}

.button,
.btn-primary,
.btn-secondary,
.btn-login {
  display: inline-flex;
  min-width: 24px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border-radius: var(--radius-pill);
  font-weight: 700;
  line-height: 1;
  text-align: center;
  transition: color var(--transition-fast), background var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast);
}

.btn-primary {
  min-height: 52px;
  padding: 0 40px;
  border: 1px solid var(--color-accent);
  background: var(--color-accent);
  color: var(--color-panel);
  box-shadow: var(--shadow-button);
}

.btn-primary:hover {
  border-color: var(--color-accent-deep);
  background: var(--color-accent-deep);
  transform: translateY(-1px);
}

.btn-secondary {
  min-height: 52px;
  padding: 0 34px;
  border: 1.5px solid var(--color-border);
  background: var(--color-panel);
  color: var(--color-text);
}

.btn-secondary:hover {
  border-color: var(--color-accent);
}

.btn-login {
  min-height: 38px;
  padding: 0 20px;
  border: 1.5px solid var(--color-accent);
  background: var(--color-panel);
  color: var(--color-accent);
  font-size: 14px;
}

.btn-login:hover {
  background: var(--color-accent);
  color: var(--color-panel);
}

.button[aria-disabled="true"],
.button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.badge,
.tag,
.fact-pill {
  display: inline-flex;
  max-width: 100%;
  min-height: 28px;
  align-items: center;
  gap: 7px;
  padding: 4px 12px;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  color: var(--color-text-soft);
  font-size: 13px;
  line-height: 1.35;
}

.badge-accent {
  border-color: var(--color-accent);
  color: var(--color-accent-deep);
}

.badge-success {
  border-color: var(--color-success);
  color: var(--color-success);
}

.status-dot {
  width: 8px;
  height: 8px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--color-accent);
}

.icon {
  width: 20px;
  height: 20px;
  flex: 0 0 auto;
}

.reveal {
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.reveal.pending {
  opacity: 0;
  transform: translateY(16px);
}

.reveal.shown {
  opacity: 1;
  transform: translateY(0);
}

.motion-counter {
  display: inline-block;
  min-width: 3.2ch;
  font-variant-numeric: tabular-nums;
  text-align: right;
}

.site-head {
  position: relative;
  z-index: 80;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-page);
}

.head-row {
  width: 100%;
  max-width: var(--content-width);
  height: var(--header-height);
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  gap: 24px;
}

.brand {
  display: inline-flex;
  min-width: max-content;
  min-height: 44px;
  align-items: center;
  gap: 10px;
}

.brand-logo {
  width: 34px;
  height: 34px;
  flex: 0 0 auto;
}

.brand-name {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 800;
  letter-spacing: -0.01em;
}

.brand-local {
  color: var(--color-text-soft);
  font-size: 13px;
  font-weight: 500;
}

.main-nav {
  margin-left: auto;
}

.main-nav ul {
  margin: 0;
  padding: 0;
  display: flex;
  align-items: center;
  list-style: none;
}

.main-nav li {
  display: flex;
  align-items: center;
}

.main-nav li + li::before {
  content: "·";
  padding-inline: 10px;
  color: var(--color-border);
  font-weight: 800;
}

.main-nav a {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  color: var(--color-text-soft);
  font-size: 14px;
  white-space: nowrap;
}

.main-nav a:hover,
.main-nav a[aria-current="page"] {
  color: var(--color-text);
}

.main-nav a[aria-current="page"] {
  font-weight: 700;
}

.head-tools {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 12px;
}

.language-control {
  position: relative;
}

.lang-switch {
  min-width: 44px;
  min-height: 44px;
  padding: 0 8px;
  border: 0;
  background: transparent;
  color: var(--color-text-soft);
  font-size: 13px;
}

.lang-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  width: 164px;
  margin: 0;
  padding: 8px;
  display: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-medium);
  background: var(--color-panel);
  box-shadow: var(--shadow-card);
  list-style: none;
}

.language-control.is-open .lang-menu {
  display: block;
}

.lang-menu a {
  display: flex;
  min-height: 40px;
  align-items: center;
  padding: 8px 10px;
  border-radius: var(--radius-small);
  color: var(--color-text-soft);
  font-size: 14px;
}

.lang-menu a:hover,
.lang-menu a[aria-current="true"] {
  background: var(--color-panel-deep);
  color: var(--color-text);
}

.nav-toggle {
  width: 44px;
  height: 44px;
  padding: 0;
  display: none;
  place-items: center;
  border: 1px solid var(--color-border);
  border-radius: 50%;
  background: var(--color-panel);
}

.nav-toggle-lines,
.nav-toggle-lines::before,
.nav-toggle-lines::after {
  width: 18px;
  height: 2px;
  display: block;
  border-radius: var(--radius-pill);
  background: var(--color-text);
  transition: transform var(--transition-fast);
}

.nav-toggle-lines {
  position: relative;
}

.nav-toggle-lines::before,
.nav-toggle-lines::after {
  position: absolute;
  left: 0;
  content: "";
}

.nav-toggle-lines::before {
  top: -6px;
}

.nav-toggle-lines::after {
  top: 6px;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-lines {
  background: transparent;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-lines::before {
  transform: translateY(6px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-lines::after {
  transform: translateY(-6px) rotate(-45deg);
}

.mobile-nav {
  position: absolute;
  top: var(--header-height);
  right: 0;
  left: 0;
  z-index: 82;
  max-height: calc(100dvh - var(--header-height));
  padding: 12px var(--gutter) 24px;
  display: none;
  overflow-y: auto;
  overscroll-behavior: contain;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-panel);
}

.mobile-nav.is-open {
  display: block;
}

.mobile-nav ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

.mobile-nav a {
  width: 100%;
  min-height: 48px;
  padding: 11px 12px;
  display: flex;
  align-items: center;
  border-radius: var(--radius-small);
  color: var(--color-text-soft);
}

.mobile-nav a:hover,
.mobile-nav a[aria-current="page"] {
  background: var(--color-panel-deep);
  color: var(--color-text);
}

.mobile-language-list {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--color-border);
}

.nav-veil {
  position: fixed;
  inset: var(--header-height) 0 0;
  z-index: 70;
  display: none;
  border: 0;
  background: var(--color-overlay);
}

.nav-veil.is-open {
  display: block;
}

.site-footer {
  margin-top: var(--section-space);
  border-top: 1px solid var(--color-border);
  background: var(--color-panel-deep);
}

.footer-grid {
  padding-top: 58px;
  padding-bottom: 48px;
  display: grid;
  grid-template-columns: minmax(220px, 1.2fr) repeat(3, minmax(150px, 1fr));
  gap: 42px;
}

.footer-brand {
  max-width: 310px;
}

.footer-brand .brand {
  margin-bottom: 16px;
}

.footer-brand p {
  color: var(--color-text-soft);
  font-size: 14px;
}

.footer-title {
  margin-bottom: 14px;
  font-size: 14px;
  font-weight: 800;
}

.footer-links {
  margin: 0;
  padding: 0;
  display: grid;
  gap: 7px;
  list-style: none;
}

.footer-links a {
  display: inline-flex;
  min-height: 30px;
  align-items: center;
  color: var(--color-text-soft);
  font-size: 14px;
}

.footer-links a:hover {
  color: var(--color-accent-deep);
}

.footer-bottom {
  padding-top: 18px;
  padding-bottom: 24px;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 12px 24px;
  border-top: 1px solid var(--color-border);
  color: var(--color-text-soft);
  font-size: 13px;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
}

.prose {
  color: var(--color-text);
}

.prose > * {
  max-width: 100%;
}

.prose h2 {
  margin-top: 64px;
}

.prose h3 {
  margin-top: 38px;
}

.prose p,
.prose li {
  color: var(--color-text-soft);
}

.prose a {
  color: var(--color-accent-deep);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.prose a.btn-primary {
  color: var(--color-panel);
  text-decoration: none;
}

.prose img {
  border-radius: var(--radius-medium);
}

.prose ol {
  counter-reset: prose-step;
  padding-left: 0;
  list-style: none;
}

.prose ol > li {
  position: relative;
  min-height: 34px;
  padding-left: 46px;
  counter-increment: prose-step;
}

.prose ol > li::before {
  position: absolute;
  top: 0;
  left: 0;
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: var(--color-panel-deep);
  color: var(--color-accent-deep);
  content: counter(prose-step);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
}

@media (max-width: 1180px) {
  .head-row {
    gap: 16px;
  }

  .main-nav li + li::before {
    padding-inline: 7px;
  }

  .main-nav a {
    font-size: 13px;
  }

  .brand-local {
    display: none;
  }
}

@media (max-width: 980px) {
  .main-nav,
  .language-control {
    display: none;
  }

  .head-tools {
    margin-left: auto;
  }

  .nav-toggle {
    display: grid;
  }

  .footer-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 768px) {
  h1 {
    font-size: clamp(28px, 9vw, 40px);
    line-height: 1.14;
  }

  h2 {
    font-size: clamp(28px, 8vw, 38px);
  }

  .btn-primary,
  .btn-secondary {
    padding-inline: 26px;
  }

  .brand-local {
    display: none;
  }
}

@media (max-width: 640px) {
  :root {
    --gutter: 16px;
    --header-height: 66px;
  }

  .no-break {
    white-space: normal;
  }

  .head-row {
    gap: 10px;
  }

  .brand-logo {
    width: 31px;
    height: 31px;
  }

  .brand-name {
    font-size: 17px;
  }

  .head-tools {
    gap: 7px;
  }

  .btn-login {
    min-height: 38px;
    padding-inline: 14px;
  }

  .section,
  .section-compact {
    padding-top: 58px;
    padding-bottom: 58px;
  }

  .footer-grid {
    grid-template-columns: minmax(0, 1fr);
    gap: 30px;
  }

  .footer-bottom {
    display: grid;
  }

  [class*="tilt"],
  .is-tilted {
    transform: none;
  }
}

@media (max-width: 360px) {
  .brand-name {
    font-size: 16px;
  }

  .btn-login {
    padding-inline: 11px;
    font-size: 13px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
    transition-duration: 0.001ms !important;
  }

  .reveal,
  .reveal.pending {
    opacity: 1;
    transform: none;
  }
}